Acetals and methods for their preparation

ABSTRACT

1,1,4,4-BIS(ETHYLENEDIOXy)-3,3-DIMETHYL-1-BUTENE (REFERRED TO AS KETENE ACETAL) IS PREPARED BY REACTING ETHYLENE GLYCOL WITH TETRAHYDRO-2-ISOPROPYL-6,6-DIMETHYLFURO(2,3-D)-1,3-DIOXOL-5-OL IN THE PRESENCE OF AN ACID CATALYST AT A TEMPERATUREOF FROM ABOUT 110* TO 170*C. THE WATER OF REACTION IS PREFERABLY REMOVED BY THE USE OF A SOLVENT WHICH FORMS AN AZEOTROPE THAT BOILS BETWEEN 110* TO 170* C. IN AN ALTERNATIVE TWO-STEP PROCESS, TETRAHYDRO-2-ISOPROPYL-6,6-DIMETHYLFURO-((2,3-D)-1,3-DIOXOL-5-OL IS REACTED WITH ETHYLENE GLYCOL IN THE PRESENCE OF AN ACID CATALYST AT A TEMPERATURE OF FROM ABOUT 60* TO 110*C. TO FORM 2-HYDROXY-3,3-DIMETHYLSUCCINALDEHYDE BIS (ETHYLENEDIOXY)ACETAL (REFERRED TO AS HYDROXY ACETAL). THE 2-HYDROXY-3,3-DIMETHYLSUCCINALDEHYDE BIS (ETHYLENEDIOXY) ACETAL IS THEN HEATED TO A TEMPERATURE OF FROM ABOUT 110* TO 170*C. IN THE PRESENCE OF AN ACID CATALYST TO GIVE 1,14,4-BIS(ETHYLENEDIOXY)-3,3-FIMETHYL-1-BUTENE. THE WATER FROM THE TWO-STEP PROCESS IS PREFERABLY REMOVED FROM THE REACTION AS IT IS FORMED THROUGH THE USE OF AN AZEOTOPIC SOLVENT. THE KETENE ACETAL IS USEFUL GENERALLY BECAUSE OF ITS REACTIVE NATURE AND FOR ITS ABILITY TO FORM OXETANE POLYMERS AND POLYESTERS. THE HYDROXY ACETAL IS USEFUL AS A GEL HARDENER, AS A CROSS-LINKING AGENT FOR USE WITH CELLULOSE DERIVATIVES AND POLYOLS, AND AS A CHEMICAL INTERMEDIATE.

United States Patent Oflice 3,787,397 Patented Jan. 22, 1974 ABSTRACT OF THE DISCLOSURE 1,1,4,4-bis(ethylenedioxy) 3,3-dimethyl-1-butene (referred to as ketene acetal) is prepared by reacting ethylene glycol with tetrahydro-Z-isopropyl-6,6-dirnethylfuro- (2,3-d)-l,3-dioxol--ol in the presence of an acid catalyst at a temperature of from about 110 to 170 C. The water of reaction is preferably removed by the use of a solvent which forms an azeotrope that boils between 110 to 170 C. In an alternative two-step process, tetrahydro-Z-isopropyl-6,6-dimethylfuro-(2,3-d) 1,3 dioxol-S-ol is reacted with ethylene glycol in the presence of an acid catalyst at a temperature of from about 60 to 110 C. to form 2-hydroxy-3,3-dimethylsuccinaldehyde bis(ethylenedioxy)acetal (referred to as hydroxy acetal). The 2-hydroxy 3,3 dimethylsuccinaldehyde bis(ethylenedioxy) acetal is then heated to a temperature of from about 110 to 170 C. in the presence of an acid catalyst to give 1,1, 4,4-bis (ethylenedioxy) 3,3-dimethyl-1-butene. The water from the two-step process is preferably removed from the reaction as it is formed through the use of an azeotropic solvent. The ketene acetal is useful generally because of its reactive nature and for its ability to form oxetane polymers and polyesters. The hydroxy acetal is useful as a gel hardener, as a cross-linking agent for use with cellulose derivatives and polyols, and as a chemical intermediate.

This invention relates to a novel compound of the ketene acetal class and to a method for its preparation. More particularly, the invention is concerned with the novel compound 1,1,4,4-bis(ethylenedioxy)-3,3-dimethyll-butene, and the novel compound 2-hydroxy-3,3-dimethylsuccinaldehyde bis(ethylenedioxy)acetal which is produced as an intermediate chemical in an alternate twostage process for producing the aforementioned ketene acetal.

For purposes of clarity, in the remainder of this specification the starting material tetrahydro-Z-isopropyl-6,6-dirnethylfuro-(2,3-d)-1,3-dioxol-5-ol will be referred to as the bicyclic acetal. This material and a method for its manufacture are disclosed in U.S. Pat. 3,564,017. The product 1,1,4,4 bis (ethylenedioxy)-3,3-dimethyl-1-butene will be referred to as ketene acetal and the alternate intermediate product 2 hydroxy-3,S-dimethylsuccinaldehyde bis(ethylenedioxy) acetal will be referred to as hydroxy acetal.

The novel ketene acetal of the invention has the formula and is useful because of its reactive nature and its ability to be polymerized to form oxetane polymers and polyesters through the ketene acetal functionality. Utility of ketene acetals in general has been demonstrated by Mc- Elvain and Curry, J. Am. Chem. Soc., 70, 3781 (1948) and Mukaiyana, J. Org. Chem, 27, 3339 (1962). The novel hydroxy acetal is valuable not only for its ability to be further dehydrated to form the novel ketene acetal, but also as a gel hardener, as a cross-linking agent for .use with cellulose derivatives and with polyols such as a polyvinyl alcohol and as a chemical intermediate.

It was quite unexpected that the feed bicyclic acetal could be reacted with a diol to form either the ketene acetal or the hydroxy acetal with a high degree of specificity. The feed bicyclic acetal contains internal hemiacetal as well as acetal functionality and its cyclic structure is very stable under most conditions. When the bicyclic acetal is treated at atmospheric pressure with an acid catalyst, in refluxing benzene as a solvent and water is azeotroped, the resultant ether dimer CH: CH3 CH3 CH: O 0 CH3 om 0 0 CH;

oxy) butanol CH 0 CH3 KO onion and 2 hydroxy-3-(l,l-dimethyl-Z,2-ethylenedioxyethyl)- 1,4-dioxane.

C0 CH3 0 O: on: o

When an acrolein dimer, also a potential u-hydroxydialdehyde, is reacted with ethylene glycol under similar acidic conditions, an approximately equal mixture of three products along with large amounts of polymeric residue is produced. Likewise, various rearrangements of the feed bicyclic acetal could be expected. An example of this is the Lobry-de Bruyn rearrangement wherein an a-hydroxyaldehyde is rearranged to an a-hydroxy ketone. In fact, it has been found that when the bicyclic acetal is heated to about -150 C. with a catalytic amount (0.5-5.0% by wt.) of sodium acetate, 2,2-dimethyl-3-oxy- 4-hydroxy butyraldehyde is formed. This compound is isolated in its cyclic hemiacetal form O- OH;

OH O by distilling it from the reaction mixture at a temperature of about 60-100 C. and a pressure of from about 0.5 to 30 mm.

It is therefore quite surprising that the bicyclic acetal will react with a diol under the relatively mild conditions of the invention to give high yields of the ketene acetal or in the alternative the hydroxy acetal. In carrying out the reaction of the invention, the bicyclic acetal is reacted with three equivalents of a diol and an acid catalyst such as p-toluenesulfonic, hydrochloric or sulfuric acid. Suitable diols include any diol wherein the hydroxy group is in the 1,2- or 1,3-position. Typically, diols such as 1,2-propanediol, neopentyl glycol, 2,2,4-trirnethylpentanediol-1,3 and ethylene glycol may be used. Any of several known methods such as direct distillation, inclusion of a dehydrating agent or physical removal by molecular sieves may be used for removing the water. A

preferred method is the use of a solvent which will for hydroxide solution and 200 ml. of water. The solvent is an azeotrope having a suitable boiling point with the removed at 200 mm. with a maximum pot temperature of liberated water. This method offers the dual advantage 60 C. The resultant 205 grams (94 percent) of oil is of removing the water and simultaneously controlling the found to be of high purity by gas phase chromatographic reaction temperature. Suitable solvents may be grouped 5 analysis and exhibits the following spectra:

by their boiling point with those having a boiling point Elm of from l-170 C., of which xylene butyl chloroace- 2920 1450 and 1060 1 tate, butyl acetate and isobutylbutyrate are examples, 'benuclear magnetlc so ance (CDCDg, 'r 9.12 (s.), 9.05

ing used in the onestep process for forming the ketene (5-), and acetal, and those solvents having a boiling point of be- 10 136mmt Y YL theoretical P actual tween 60-110 0., such as benzene, dichloroethane, di- P oxane and 1,2-diethoxyethane being utilized in the initial EXAMPLES step of the two-step procedure wherein the hydroxy acetal is formed as an intermediate. In the two-step process, Examples 2-5 show that other acidifying agents as well the hydroxy acetal is subsequently reacted in th pres- 15 as other glycols can be used in the reaction. The reaction ence of a solvent of the higher boiling group (1l0170 lv s (B-P- rang 5 4 0 C.) f Examples 2-5 pro- C.) to form the ketene acetal. Obviously, if the hydroxy duce the hydroxy acetal. The procedure of Example 1 is acetal itself is desired, the second step is unnecessary. followed except that the solvents, acidifying agents and The relationship of the oneand two-step process can be glycols listed are used.

Percent Example Solvent Acidiiying agent Glycol yield 2 Benzene p-Toluenesulionic-.- Neopeutyl glycol 80 do-. Hydrochloric do 75 Dioxane Sulfuric Lil-propylene glycol--- 66 5 l,2-dichloroethane p-Toluenesulfonie.-- Neopentyl glycol 82 better understood by the following multiple equations EXAMPLE 6 wherein the route marked A characterizes the one-step 0 Example 6 Shows a preferred method f the process, the route marked B characterizes the first step tion of 1, 4 -3,3. 1 1

0f the p Process, and the route marked C chafactene and shows that the bicyclic acetal can be converted in terizes the second step of the two-step process. one step to the ketene acetal.

CH3 CH3 p l n t 110 0 CH: CE W 3 A 0 Acid catalyst 0 O 0 3OH2CH2 H0 cH(cH,) 31120 $11 (la 0 CH: O CH: O

Ethylene 2 O 3 glycol Solvent Solvent A (13.1. tic-170 o. (8.1. 110-170" 0.

Acid catalyst Acid catalyst o CHa Oj {:0 otau o-:l L-O' iHa 0 O: iHs O CH: O :l CH: 0

iHzQ

Catalyst concentration is not critical and may range from 1,1,4,4-bis(ethylenedioxy) 3,3 dimethoyl 1 -bu- 0.001 to 2 mole percent based upon the moles of starting tene.In a 500 ml., round-bottom bask is placed 6-7.4

material. A preferred concentration is 0.01%. grams (0.33 mole) of the bicyclic acetal, 68 grams (1.1 This invention is further illustrated by the following mole) of ethylene glycol, 200 ml. of xylene, and 0.29 ml. examples which are set forth for purposes of illustration of p-toluenesulfonic acid. A Dean-Stark trap and cononly and should not be construed as limiting the invendenser is attached, and reflux is continued for 4 hours. tion in any manner. The total water collected is 24 ml. (1.33 moles). The so- EXAMPLE 1 lut1on is treated with 1 gram of sodlum acetate, placed under a 10-plate Oldershaw column and distilled. A color- The purpose of this example is to describe the method less liquid, 40.0 grams (60%) with boiling point 105 of choice for the preparation of 2-hydroxy-3,3-dimethyl- C./2 mm. is realized; succinaldehyde l,1,4,4-bis(ethylenedioxy)acetal. film 2-l1ydroxy 3,3 dimethylsuccinaldehyde 1,l,4,4-bis- Am 3080 1685 1270 and 110 (ethylenedioxy)acetal.-In a 2-liter flask equipped with a nuclear magnetic resonance (CDCDB Dean-Stark trap and condenser is placed 202 grams (1 and (5'); mass spectrometar m/e (P) mole) of the bicyclic acetal, 184 grams (3 moles) of ethylene glycol, 500 ml. of benzene, and 0.2 gram of p- EXAMPLES 7-9 toluenesulfonic acid. The contents are vigorously stirred Examples 7-9 show that other acidifying agents, glyunder a nitrogen atmosphere and refluxed for 15 hours. cols and solvents with RP. range 110170 C. allow the The total water removed is 3.2 moles. The solution is synthesis of the ketene acetal in one step. The procedure cooled to room temperature, treated with 0.2 gram of of Example 6 is followed except that the solvents, acidifypyridine, and washed with 100 ml. of 1 percent sodium ing agents and glycols listed are used.

Ex- Percent ample Solvent Aeidifying agent Glycol yield 7 Xylene Hydrochloric N eopentyl glycol 62 8 Isobutylbutyrate-. p-Toluenesulfonie. Ethylene glycol 43 Q Xylene do 21 2,2,4-tn'methylpentane-1,3-

diol.

EXAMPLE 10 Example 10 shows that in addition to the direct synthesis of the ketene acetal, the hydroxy acetal can be subsequeutly converted to the ketene acetal.

l,1,4,4-bis(ethylenedioxy) 3,3 dimethyl 1 butene.In a 500 ml. flask is placed 19 grams (0.087 mole) of 2 hydroxy-3,3-dimethylsuccinaldehyde 1,1,4,4 bis- (ethylenedioxy)acetal, 150 ml. of xylene, and 0.12 gram of p-toluenesulfonic acid. A Dean-Stark trap and condenser is attached, refiux i continued for 3 hours during which 0.08 mole of water is collected. Work-up is identical to Example 2 and distillation yields 14 grams of the ketene acetal.

Although the invention has been described in detail with particular reference to certain preferred embodiments thereof, it will be understood that variations and modifications can be efiected within the spirit and scope of the invention.

I claim:

1. A method for preparing 1,1,4,4-bis(ethylenedioxy)- 3,3-dimethyl-1-butene wherein tetrahydro-2-isopropyl-6,6- dimethylfuro(2,3-d)-1,3-dioxol-5-ol is reacted at a temperature of from about 110 C. to about 170 C. with at least three equivalents of a diol wherein the hydroxy groups are in the 1,2- or 1,3-position in the presence of an acid catalyst selected from the group consisting of ptoluenesulfonic, hydrochloric and sulfuric acid and wherein the water liberated during the reaction is continuously removed.

2. The process of claim 1 wherein the reaction is conducted in an inert organic solvent having a boiling point of from about C. to about C.

3. The process of claim 1 wherein the diol is selected from the group consisting of ethylene glycol, 1,2-propanediol, neopentyl glycol and 2,2,4-trimethylpentanediol-1,3.

4. The process of claim 1 wherein the catalyst concentration is from about 0.001 to about 2.0 mole percent based on the moles of starting material.

5. The process of claim 1 wherein the catalyst concentration is about 0.01 mole percent based on the moles of starting material.

6. The process of claim 1 wherein the catalyst is ptoluenesulfonic acid.

7. The process according to claim 1 wherein the diol is ethylene glycol.

8. The process of claim 2 wherein the inert organic solvent is selected from a group consisting of xylene, butyl chloroacetate, butyl acetate and isobutylbutyrate.

9. The process of claim 2 wherein the inert organic solvent is xylene.

DONALD G. DAUS, Primary Examiner J. H. TURN IPSEED, Assistant Examiner US. Cl. X.R.

PO-1050 1 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,787,397 Dated January 22 1974 lnvemods) Anthony McCollum It is certified thaterror appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Columns 3 and 4, delete the formula and insert:

Solvent d (3.1 60ll0C H o- -o Ethylene Glycol CH5 O- I 3 H2O CH5 o- 2. Solvent Y Q A (B.P. ll0l70C.) Solvent Acid Catalyst (B.P. llO-l70C.)-

Acid Catalyst Column 4, line 67 after 5.26 5. insert --6.l2(s.)

Signed and sealed this 9th dayof April 197b,.

(SEAL) Atte st 2 EDWARD M .FLETGHER, JR. C MARSFALL DANN Attesti Officer Commissioner of Patents 

